It is proposed to use the Gunn rat as an animal model for the perturbing effects elicited by unconjugated bilirubin in the development of the neonatal brain. The study will focus on selected aspects of cerebellar protein synthesis, levels of GABA, GABA-T, and GAD and the morphogenetic perturbations caused by brain bilirubin. Studies of protein synthesis in bulk isolated Purkinje cell bodies and granule cells isolated from kernicteric and littermate control Gunn rats will be carried out. The development and migration of granule cells will be examined by autoradiographic and histological techniques. Our earlier finding of bilirubin myelin basic protein interaction will be examined with respect to the affect of this interaction on myelin composition, development and stability. The objective of this research is the elucidation of the various pathways by which unconjugated bilirubin interferes with brain development and neurochemistry.